Casting and process of making same.



J. H. BAM BERG.

CASHNG AND PROCESS OF MAKING SAME.

APPLICATION FILED MAR. 1. 1916.

1,296,589. Patented Mar. 4,1919.

5 SHEETSSHEEI I.

Jill! ll lllll J. H. BAMBERG. CASTING AND PROCESS OF MAKING SAME.

APPLICATION FILED MAR. T, I9IE. 1,296,589. Patented Mar. 4.1919.

5 SHEETS-SHEE12 J. H. BAMBERG. CASTING AND PROCESS or MAKING SAME.

APPLICATION HLED MAR. 7. I916. 1,296,589. Patented Mar. 4,1919.

5 SHEETS$HEET 3. 9 8 5' 5 3 4 3 4 J. H. BAMBERG. CASTING AND PROCESS OF MAKING SAME.

APPUCATION FILED MAR. 7. I916. 1,296,589. Patented Mar. 4,1919.

5 EEEEEEEEEEEE 4.

a (@QM/ I J. H. BAMBERG.

CASTING AND PROCESS OF MAKING SAME. APPLICATION FILED MAR. 7, 19:6.

1,296,589. Patented Mar. 4, 1919.

5 SHEETS-SHEEI 5..

VII

UNITED STATES PATENT OFFICE.

JOSEPH H. BAMBEBG, OF 'IONAWANDA, NEW YORK, ABSIGNOB TO THE ALUMINUM CASTIHGS COMPANY, OF CLEVELAND, OHIO, A CORPORATION 01 OHIO.

CASTING AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented Mar. 4, 1919.

To all whom it may concem:

Be it known that I, Josurn H. BAMBERG, a citizen of the United States, residin at Tonawanda, in the county of Erie and tate of New York, have invented certain new and useful Improvements in and Relating to Castings and Processes of Making Same, of which the following is a specification.

This invention relates to a process of making castings, more particularly castings having hollow sections with internally projecting bosses, webs, ribs and extensions. or either of them, and the product resulting from said process.

While of more general application in many of its aspects, the invention has in view and is adapted to the production of skirted pistons, such as are used in internal combustion motors.

One of the objects of this invention is to provide a process of making castings of metal or metallic alloy of relatively low specific gravity, in which, preferably, the metal is poured into the mold under atmospheric conditions and flows into themold cavity under gravity action and in which the resulting castings are relatively non-porous, free from entrapped air and other gases. and

oxids and other foreign materials and are capable of easy machining to provide eflicient and durable bearing surfaces.

Another object of the invention is to provide a process especially adapted to the making of a casting having a hollow section with relatively thin walls and internall extending bosses, ribs or projections, or either of them, such as a cast skirted piston for internal combustion engines, wherein the parts forming a mold cavity may be rapidly and easily separated from the casting and their tem eratures controlled to regulate, as desir the times during which they are to contact with the casting and to-produce different internal structural characteristics in different parts of the casting.

A further object of the invention isto provide an improved process of producing relatively light weight piston castings from aluminum alloys, or other metallic allo of light weight and high heat conductivity, w ich piston castings shall be substantial non-porous, with various parts havi di ferent internal structural characteristics as desired and composed in their entirety of a.

"= volume of metal and which, when finished and used within the linders of internal combustion engines, wil not collect carbon to the same extent as do iron istons and will, because of their fine graine structure, take and retain a relatively high polish.

Another object of the invention is to provide a process of casting in permanent sectional molds skirted pistons of metal or metallic alloy of relatively low specific gravity, whereby the said castings can be produced more rapidly and cheaply, of greater uniformity, and requiring loss volume of metal than has heretofore been possible.

Another object of this invention is to provide a process of making piston castings for internal combustion motor pistons from an alloy of aluminum and magnesium, or either of them, containing co per, tin. zinc, iron, manganese, titanium, nickel and silicon, or either or any of them, and in whichthe resulting structure will be relatively finegrained, non-porous and free from entrapped air and other gases and from oxids and other foreign materials.

Another object of my invention is to provide a process of making piston castings for internal combustion motors using metallic alloy of relatively low specific avity and high coeflicient of heat conductlvit and in which there will be a relatively smal amount of eutectic substantially surrounding the excess substance in the casting in a manner to provide eflicient and durable machined hearing surfaces.

Another object of my invention is to pro vide a process of making piston castings for internal combustion motors using a metallic alloy of relatively low specific gravity and high heat conductivity and causing (a) the casting to set progressively within the mold cavity, while maintaining the portions of the freezing metal within the mold cavity which are still liquid in communication with a source of liquid metal outside the mold cavity to produce a non-porous structure and (b) the setting to take lace with suflicient rapidity to produce a re atively fine-grained structure. 7

Other objects of my invention are to 1'0- vide a skirted piston casting of meta or metallic alloy of relatively low ecific grav.

.ity and a relatively high coeficient of heat conductivity and which piston is comparatively non-porous and free from entrapped air and other gases and oxids and other oreign materials, and has different internal structural characteristics at diflerent sections as desired, which when machined and used in the cylinder of an internal combustion motor, will not collect carbon as readily as an iron piston and will take and retain a relatively high polish because of its finegrained structure, and which will not disintegrate under ordinary usage in an internal combustion motor.

Another object of my invention is to provide a skirted piston casting made of a I metallic alloy of relatively low specific gravity and high heat conductivity and in which casting there is a. relativel small amount of eutectic which substantia ly surrounds the excess substance in the castin in a manner to provide eflicient and dura le machined bearing surfaces.

Another object of this invention is to provide a piston casting of an alloy of aluminum and other elements such as magnesium, co

r and iron, having a structure relative y ne-grained, non-porous and free from entrapped air and other gases and from oxide and other foreign materials.

Other objects of my invention will be obvious to one skilled in the art from the description of it hereinafter given.

I prefer to carry out my invention by first assembling the necessary parts of a mold, all of which preferably are made of metal to provide chilling or setting surfaces, including core sections, to shape a mold cavity which will form a piston casting having a head and a cylindrical portion and also preferably internally extending hollow wrist pin bosses. It will be understood that the walls of the mold cavity should be suitably coated or treated in any well known manner to insure proper setting of the metal poured into the mold cavity and easy and rap1d separation of the casting from said Walls. Each metal core section for a wrist pin boss should be movable bodily toward and from the axis of the mold cavity in which the cylindrical section of the piston is formed to permit its insertion into the mold cavity and withdrawal from the casting by bodily endwise movement ,at an angle to said axis. The core for the cylindrical portion of the piston should be made in three or more parts or sections slidably correlated, one of which is centrally disposed relative to the others and freely movable into and out of the mold by bodily endwise movement along the axis of the mold cavity, Whereas some or all of the other parts should be recessed to receive the inner end of one of the core sections for the wrist pin bosses and should be movable, 1) bodily laterally relative to the axis of the mold cavity until it is free from the adjacent wrist pin boss, and (2) bodily endwise along the axis of the mold cavity, until withdrawn therefrom.

I have found it advisable to heat and maintain heated the parts of the mold which form the mold cavity. The core sections for the internally projecting bosses preferably are maintained at a lower temperature than the other walls for the mold cavity so as to of the casting to be ma c. It will be understood that the respective core sections can readily be maintained at temperatures differing from each'other and mm the temperatures of the other parts of the mold; by reason of the fact that the core parts are periodically removed from the mold and while removed can be subjected to any suitable temperature conditions; as, for example, to the coolin action of water or the atmosphere, or to t e mild heat of a torch or furnace.

Next, I cause suitable molten metal to enter the mold cavity. Preferably I pour the molten metal by hand and cause it to flow into and fill the mold cavity under the action of gravity. I prefer to have the metal enter at one side of the mold cavity at points substantially equidistant from the internally projecting recesses for the wrist pin bosses, so that it may flow in opposite directions, that is, both clockwise and anti-clockwise, from its point of entrance, to fill the mold cavity from bottom to top, the mold being suitably vented to permit the escape of air and other gases.

The shape of the mold cavity, volume of metal in the walls of the mold cavity, including core sections, temperature of the mold cavity walls and temperature of molten metal poured, should be such that setting of the metal within the casting will take place progressively from points relatively remote from those at which the molten metal conditions I insure that it will be substantially non-porous because of any cavities in it caused by c stallization shrinkage.

The mold cavity being filled, I next remove the core pins or core sections from the internally projecting hollow bosses by bodily endwise movement, respectively. Next I remove the main core sections. he central one is withdrawn first merely by bodily endwise movement a ong the axis of the mold cavity. Next I remove the core sections into which extend the hollow inwardly extending bosses on the casting, (1) by lateral bodily ll'l0VB ment of each said section and then (2) byoutward or longitudinal endwise movement thereof relative to the axis of the mold cavity. Next I separate the remaining parts of the mold so as to free the casting.

In actual practice inmakin aluminum alloy piston castings I have ound it desirable relatively quickly to chill or set the internally projecting hollow bosses by having the core sections or pins which they embrace of the desired temperature to cause the quick chilling or setting of the same. For example, with some piston castings which I have been making by this process, .I have found from fifteen to thirty seconds to be a suflicient length of time to leave the core pins for the wrist pin bosses in the mold I have found it advisable to remove the main core sections in from thirty seconds upwardly, depending upon the design of the casting and the thickness of metal at various sections thereof. One index of the time for removing the main core sections, which may, under certain circumstances, be relied upon, will be the time approximately when the shrinkage due to crystallization losses takes place. for example as indicated by the shrinkage in the gate at such time.

My process is especially adapted for making trunk or skirted pistons from aluminum alloys. Such piston castings should have good bearing qualities and also ample tensile strength to enable them to withstand the heavy stresses to which pistons, especially of internal combustion motors, are subjected in operation. By using aluminum alloys of suitable composition and subjecting them to suitable time-temperature treatment in casting, I have succeeded in producing castings with internal physical structures that insure the desired bearing qualities and strength. Said internal structures are characterized by a relatively small amount of eutectic which substantially, though pref- 'erably not entirely, surrounds the excess substance of the alloy. Furthermore, as will hereinafter appear, alloys with eutectic and excess substance thus roportioned and relatively arranged lend tliemselves admirably, in my improved process, to the elimination of porosity due to crystallization shrinka e.

Satis actory alloys for the production of walls of the mold cavity should be so 8 such piston castings may contain about eighty per cent. or upward of aluminum, the remaining constituents being iron, titanium, silicon, magnesium, zinc, tin, (OPPQI', nickel and manganese, or any of them, as may be found advantageous for the particular piston job having the desired internal structural characteristics. Aluminum alloys which have been found especially suitable for piston castings contain, in addition to the aluminum, copper up to 11.0%, magnesium up to 1.0% and iron up to 1.5%. These alloys may also contain a small amount of silicon which appears as an unavoidable impurity in commercial ingot aluminum.

Such an aluminum alloy containing approximately 10.0% of copper, 1.25% of iron and 0.25% of magnesium I have found to be in a satisfactory molten state for pouring at about 1380 degrees Fahrenheit. At this temperature the alloy will be sufiiciently liquid to pour freely and may be caused to flow under the action of gravity into the mold cavity so as to completely fill the same, providing that the temperatures of the walls of the mold cavity are maintained at about the temperatures above indicated.

The sections or parts constituting the aped and disposed relative to the casting formed in the cavity that, (1) they may be quickl and readily separated therefrom and (2 the separation may take place without undue jarring of the casting; since the freesing range of an alloy of this character is re atively large, and the eutectic is the last portion of the cast structure to freeze, it is essential in. producing a sound casting free from cracks and cavities, that jarring should be avoided which would be of a character sufficient to disturb the proper relationship of the eutectic to the excess material and cause cracks or fissures in the cast ing or poorly knit surfaces. 1 The piston castings resulting from the carryin out of my improved process, using a metal ic alloy having relatively low specific gravity and relatively hi h coefficient of heat conductivity, for examp e, an alloy of aluminum, magnesium, iron and copper, such as above referred to, are peculiarly adapted. for use in internal combustion motors. Their walls may, if desired, be made relatively thin, so that the piston as an entirety is'relatively light. The structure is fine-grained and practically non-porous, the eutectic substantially surrounding the excess material in such manner as to provide a durable and relatively efficient bearing surface without material sacrifice of tensile strength. I have been unable to note any disintegration in the structure of these castings after thousands of miles of severe service in relatively high speed automobile motors of the internal combustion type.

Furthermore, the internal physical structure of the casting characteristic of the above mentioned relation of the eutectic and excess substance is not changed by the working temperatures of the internal combustion motor to which said castings are subjected. These piston castings require relativel little machining in order to repare them or use inside the cylinder wali; of an internal combustion motor. Their structure is finer grained and less orous than the structure of pistons made I) any other process of which I have know edge. Furthermore, the uniformity of product resulting from the process is greater than with any other process known to me. As the connection between the connecting rod and the piston is made through the instrumentality o a wrist pin fitted into the-wrist pin bosses, I have ound it of articular advantage to have the structure of these bosses that which results from relatively quick setting of the metal in them. As above indicated, the diiference in temperature between the molten metallic allog as it is poured and the temperature at w ich the core pins for the wrist pin bosses is maintained, is approximately one thousand degrees Fahrenheit.

With respect to the relation of theeutectic and excess substance in my improved castings, I may observe that while the eutectic substantially surrounds the excess substance as stated above, I believe it is desirable that it shouldnot entirely surround and completely isolate said excess substance' for, by avoiding such complete isolation of the excess substance, I believe greater tensile strength is secured.

I believe that progressive setting of the metal in the casting is one bf the important factors in reducing porosity, and I have had in mind, in my improved process, to have the setting take place progressively within the mold with that object in view. It is my opinion that when any liquid metal becomes completely surrounded with solid metal, during freezing, its solidification will be accompanied by a contraction of about three to six per cent. of its total volume, porosity accordin 'ly resulting. I In my improved process, uring the solidification period,-,the portions of the freezing metal still liquid are in communication with a source of liquid metal without the mold cavity,,so that cavities which would normally form in the casting by crystallization shrinkage are filled up.

The existence of an eutectic in a metalllc alloy for casting purposes, because of the low melting point of the eutectic, is peculiarly advantageous in reducing the amount of porosity in the casting, particularly where the liquid portions of the freezing metal are in direct communication with other liquid metal, as provided by my improved process, which permits the crystallization shrinkage within the casting to be filled up or taken care of from molten metal without the mold cavit proper. During the freezing of the meta in the casting made by my improved process, at substantially no time is liquid metal within the casting isolated from other liquid metal by solid ntions.

It will be understoo that the core sections for the wrist pin bosses and the'main core sections always should be removed prior to the time when the shrinkage of the metal in the mold cavit upon the core section would make it di cult to remove said section from the casting.

In order to keep the molten metal outside of the mold cavity in proper liquid condition to compensate for shrinkage losses in the mold cavity, the walls containing the gate in which the said outside metal collects may be maintained at a higher temperature than the walls constitutin the mold cavity, or the adjacent parts 0 the mold which form the walls of the mold cavity proper.

Having described the steps of my recess, I will now describe ways and means or carrying out those steps and the product resulting therefrom.

Figure 1 is a plan view of a mold suitable for use in carrying out my improved process, parts being broken away.

Figs. 221ml 3 are fragmentary sections on the line 2-2 of Fig. 1, the former showing the metal partly poured and the latter showing the casting completely poured.

Fig. 4 is a side elevation of the mold, part 100 of the view being in section on the line 4-4 of Fig. 1, showing the core pins removed.

Fig. 5 is a sectional view of the mold with the core removed.

Fig. 6 is a top plan view of the mold with 106 the mold members separated and the casting secured to one of them.

Fig. 7 is a perspective view of the casting, after it is removed from the mold, showing detached that part of the sprue which is im- 111 mediately broken off as the casting is removed from the mold.

Fig. 8 is a horizontal section on the line 8-8 of Fig. 3. r

Fig. 9 is a perspective view of the main 1 core section.

Fi 10 is a horizontal sectional view on the line 10-10 of Fig. 3, showing the center core section removed and two of the side core sections swung laterally to illustrate the 121 manner of freeing the same for removal.

Fig. 11 is a perspective view of two side sections of the core.

Fig. 12 is a bottom plan view of the assembled core. 126

Fig. 13 is a perspective view of a skirted or cup-shaped piston, after the sprue has been removed.

Fig. 14 is a transverse sectional view through the piston. 130

preferably comprises a base member 2 and com lementary members 3, 4, movab e on the ass member 2 toward and from each other. The base member 2 may. comprise a platform or base plate 2, the central portion of which is suitably surfaced to form the bottom of the mold cavity A. The base member 2 is by preference mounted on feet or standards 2".

Each of the complementary members 3, 4, may comprise a side wall 5, end walls 6, 7

and top and bottom walls 8 and 9, respectively. These walls may be integrally formed, as shown in the drawings. The walls 6, 7, 8 and 9 of each member project outwardly from the rear face of the wall 5 to form a heating chamber 9', the outer side of which is formed by a plate 9 fixed in a well-known manner to the end edges of the walls 6, 7 and 8 by bolts 9. v

3, 4', indicate handles, connected in any well known manner to the plates 9 for the respective mold members 3, 4, whereby the latter can be conveniently moved to and from the operative position.

The wall 5 of the mold member 3 is adapted to engage with the wall 5 of the member 4 when said members are moved together, as shown in Fig. 1. The wall 5 of each mold member 3, 4, is provided between its ends with a semi-circular portion 5 which in cooperation with the similar semi-circular portion of the other mold member, and the surfaced portion of the base plate 2", forms the outer wall of the mold cavity A. The wall 5 is, in the preferred form of the invention, relatively thick in order that it may be capable of retaining suflicient heat to make the mold etlicient for casting pistons or other cup-shaped articles from various metals and alloys, such as aluminum alloys. At 2, the base plate 2 is provided with an annular shoulder and the bottom walls 9 of the mold members 3, 4, are recessed at 9 to receive the shoulder 2, whereby the mold members 3, 4, are properly alined relatively to each other and also centered on the base plate 2' when moved together, as shown in Fig. 1.

10 indicates auxiliary devices for alining and centering the mold members 3, 4. The auxiliary devices 10 may be "used in connection with and auxiliary to the devices 2 and 9', or as a substitute therefor. The auxiliary devices 10 preferably comprise a pair of upwardly projecting stationary ins 10 arranged near opposite sides of t e base plate 2 and recesses 10 formed in the opposing faces of the walls 5 of the mold members 3, 4. The pins 10 and recesses 10" cooperate to cause the positioning of the mold members 3, 4, at a predetermined position each time they are moved together, it being necessar to so position the members 3, 4, that their recesses 10 will receive the pins 10" to bring them face to face to form the mold cavity A.

11 indicates as an entirety a permanent sectional core adapted to removably fit within the mold cavity A. The sides of the core may be slightly tapering to facilitate its removal.

The core 11 preferably comprises a plurality of parts made of steel, though other suitable material may be used; in the illustrated example it consists of a main or center section 11 having curvilinear end walls 11, and pairs of segmental sections 11 arranged at opposite sides of the center section 11. Each section of each pair of side core sections 11 at either side of the center section is bodily laterally movable after the center section 11 hasbeen removed, as illustrated in Fig. 10, to permit its disengagement from inwardly projecting parts on the casting prior to its endwise or axial movement upwardly for withdrawal purposes. Each core section 11", 11, maybe rovided with a handle 11, 11", respective y, to facilitate handling thereof in assembling anddisassembling the core.

The construction of the core in sections, as herein disclosed, provides for the easy and rapid removal of the sections where the casting. has inwardly extending tubular or hollow bosses, ribs or other inwardly projecting members, desired for any purpose. As shown in Fi 11, the cavity a for each wrist pin boss is ormed in the adjacent side core sections 11, one-half of the cavity being formed in each section by cutting away a portion of the core section wall. As will be understood, this construction permits these sections 11 to be swung away from each other in order to move their lower ends from beneath the adjacent boss of the casting in the mold cavity, and to do this, where inwardly extending ribs are carried by the casting, without defacing or mutilating such 1'] S.

In the form of construction shown, I have made provision for two heat dissipating ribs which extend across the inner face of the piston head preferably at right angles to each other. Such ribs may also be used for strengthening pu oses. One rib is provided for on the casting y a ove 11 formed in and extending longitu y'nally of the lower tions to end of the center core section 11'; the other rib is provided by a groove 11 formed in the lower end of the center section 11' and extending transversely to the groove 11" and b 11 which aline with the groove formed in the opposing faces be tween and adjacent to the lower ends of each pair of side core sections 11. Where it is desired to have the transverse rib extend upwar to the as shown in the drawings, t e o posing faces of the side core sections may cut away as indicated at 11'.

In Fig. 10 I have shown a circle of substantially the diameter of the thickness of the inwardly extending ribs or webs. The walls of the core sections 11 which extend toward this circle are preferably formed on lines tangential to the circle, as are also the walls of the section 11 whichengage therewith. This construction insures that when the sections 11" are swun bodily to remove them from the adjacent 0s 6 their lower ends will practicall engage flat with the side of the rib or wa toward which they are moved rather than make a oint engagement therewith. The purpose of this construction is two fold; first, it permits of maximum lateral swin 'n movement of the side core secac1 itate their withdrawal from a casting in the mold; second, in the event any molten metal flows in between the opposing faces and forms a fin (which may happen if the sections do not fit tight] together or become worn) the fin is cause to project from the inner face of the casting at substantially right angles to a plane extendin tangentiall of the castin at the point 0% union of the n therewith. %Nhen so disposed the fin may be broken or sheared off without injury to the adjacent walls of the casting; whereas I have found in practice that fins extending in other directions away from the inner face of the casting due to the construction of the core sections and disposition of their opposing or engaging faces, have a stronger union on. one si e of the fin with the adjacent wall of the casting than on the other so that when such a fin is rem ved -by breaking or shearing it ofl, it will carry with it portions oi the metal forming the casting wall to which it was most strongly connected instead of making a clean break or shear. Under such circumstances the removal of the fin will materially damage the casting.

In carrying out this feature of my invention, it will e noted that the opposite side faces of the center section 11 are provided with walls 11" which extend in a direction approximately radially of the axis of the core and that the opposite side walls 11" of each side core section are shaped to fit against each other and the walls 11*, respectivel 12 indicates devices for swingably supporting the side core sections 11 on the mold members 8, 1. These devices preferably com rise flanges, one for each section, exten g around the outer edges thereof. When the core sections 11-are assembled in the mold cavitgsA, the flanges 12 on age the top walls 8. the latter are flat, t ey permit the flanges 12 to slide thereon when the sections 11 are swung laterally as shown in Fig. 8, and this guide the sections 11 bodily laterally.

13 indicates devices preferably fl secured to or formed integrally with the center section 11'. These flan extend around the curved end walls 11 o the core sections 11 and rest upon the top walls 8 to support the said section in proper position.

14 indicates rojecting members carried by and preferably formed integrally with the main or center core section 11. The members 14 are arranged. above the flanges 13 and extend beyond their free edges so as to leave a space between each projecting member and the adjacent top wall 8. In actual lpractice, the core sections 11, 11, are usua y wedged together very tightly within the mold opening above the cavity A. The purpose of this construction is therefore to provide devices with which a tool or lever may be engaged to pry out the core section. I prefer to provide a projecting member 14 at either curved end of the core section 11.

15 indicates a pair of permanent core sections or core pins arranged to project into the mold cavity A to form openings in or through the bosses formed by the cavities a in the core sections 11. The core pins 15 preferably comprise rods, each of which extends through a pair of alined openings formed in a wall 5 and adjacent plate 9. At their inner ends the rods preferably engage the core sections 11 to limit their inward movement when ositioned as shown in Fig. 1. Near their inner ends, the core pins 15 may be slightly tapered to permit ready removal and disengagement from the castin 15 indicates a collar fixed in any suitab e manner to each rod 15. The collar 15 is spaced from the adjacent plate 9 to permit the use of a p ing tool to be used to force the rod outwar y and remove it when necessary. Each rod 15 is provided on its (fmter endwith a handle 15 of any suitable 16 indicates devices which o6perate to core 11 is moved. The key 16' may be connected to the core section 11 by countersunk screws, as shown in Fig. 3. The groove 16 may be formed by cutting away the adjoining faces of the walls 5 said faces, in the construction shown being formed by bushing members 23 which will be later described.

19 indicates devices for locking the mold members to ether so that they may be held in rigid re ationship while casting takes place. I may provide a set of locking devices at either side of the mold. Preferably, each set of devices 19 comprises a lug or projection 19, fixed in any suitable manner to one of the mold members, such as the member 3, and a member 19 pivotally mounted on the other mold member and swingable into latching engagement with the lug 19. The member 19 carries a hook or arm which engages the pin 19. The pivoted member is adapted to be driven downwardly against the pin 19 and the pin enaging face of the arm is wedge shaped, so t at when the member 19 is struck with a hammer or equivalent tool, the inclined face will serve to force the mold members 3, 4, tightly together and maintain them in such position.

In operation, the walls of the mold, including core arts, which constitute the walls for the mol cavlty are suitably coated or treated in any well known manner to reduce as much as possible agitation of the molten metal as it flows into contact therewith and to insure proper setting of the metal within the mold cavity. The mold members 3, 4, are usually moved together, then the locking devices 19 are moved into operative position ready to be driven or forced into latched position and the pairs of side sections and the center of the core 11 are assembled in the mold, after which the members 19 are hammered to draw and lock the mold members together. The core sections 15, 15 are then introduced into place.

20 indicates the gate for the mold; it may be of any desired form. The gate is preferably formed by cutting away the ad oining faces of the opposing walls 5, so that when the members 3, 4, are assembled to other the cutaway portions form agate of t e desired shape.

The shape and construction of the 20 herein shown for illustrative purposes I believe to be the sole invention of A. B. Norton, of.Detroit, Mich. As such invention will form the subject-matter of a separate application, further description of the gate herein will not be necessary.

Where the character of the castings, the mold parts and the metal poured, or either thereof, make it necessary or desirable to heat the mold in carrying out the casting opgate eration, I provide means, indicated as an entirety at 21, for heating the mold parts or walls to and keeping them at the desired temperatures. The heating means 21 may comprise suitable burners 21' to which are connected gas and air supply pipes 21", 21, respectively. Each supply pi e has a flexible connection and is provide with a valve 21 of any suitable construction. The open or free end of the burner 21 is preferably spaced from the adjoining mold member but is arranged to project the flame into and through an opening 9 formed in the adjacent plate 9, whereby it may impinge against the wall 5 within the chamber 9". I have for illustrative purposes shown heating means 21 for each mold member 3, 4, and so arranged that the flame will impinge directl on the portions of the adjacent wall 5 in w ich the gate 20 is formed. As a result of this construction, the metal flowin through the ate 20 to the mold cavity will be kept rom premature setting.

22 indicates a bracket for supporting each heating means 21. The bracket is fixed in a well known manner to one wall of the adjacent mold member, such as the wall 7 Being connected to and movable with the mold members, the brackets maintain the burners 21 infixed relationship to the mold members and thus permit the latter to be operated in carrying out the casting operations'.

I provide improved means for venting the mold cavity A to permit the ready escape of air or gases as the molten metal flows into the cavity and to effect the run of the metal to all parts of the cavity. The sectionality of the mold structure lends itself admirably to the carrying out of this feature of the construction, since it permits the mold cavity to be vented without regard to the shape and construction of the casting.

I have chosen to illustrate two difierent examples of venting means. Oneof these examples is shown in Figs. 2, 3, f5 and 8. Referring to these figures, 23 indicates an insert and 23 indicates a recess formed in the wall5 of each mold member 3, 4, to receive an insert 23. The inserts 28 are mounted above the mold cavity A in the opening formed by the semi-circular walls 5. They are of curvllinear shape and, as shown, form the upper walls of the opening through which the sections of the core 11 are inserted into and removed from the mold cavity A. The inserts are preferably arranged to giroject inwardly beyond the outer wall 0 the cavity A (see Fig. 3), whereby their lower ends form the upper end walls for saidcavity. 23* indicates a pluralit of grooves formed on the lower ends 0 the inserts. These oves may extend in a direction radial r ative to the axis of the 'mold cavity. The grooves 23" are referably etched or otherwise formed in t e surfaceof the insert so that they will be small enough to preclude molten material from flowing through them but large enough to permlttthe free escape of air or gases from the mold cavity A. At

. 23 the lower outer corners of the inserts 23 are cut or beveled away to form in coiiperation with the walls of the recess 23 a channel 23 into which the outer ends of the grooves 23" lead. 23 indicates recesses or rooves formed in the outer surfaces of the inserts 23. The recesses 23 extend from end to end of the inserts and in cooperation with the adjacent walls of the recesses 23 form outlets or vents leading from the channel 23 to the outside atmosphere.

tively, when the latter are in position. It

Y j acent shou from the cavities 11 will be noted that the vents 28 and 23 lead from the upgcr outer and inner corners of the cavity This construction ermits air and other gases to escape from 0th of these points as the metal is poured, and insures that themetal will run into and completely fill the cavity and form a casting of the desired shape. The inserts 23 may be fixed in the recesses 23" in any suitable manner, preferably b screws, the heads of which are countersu as" shown in Fig. 5. Another form of venting is shown in Figs. 2, 3 and 6. By this latter form, I illustrate means for venting a cavity formed in a core section or sections. In these figures, 24 indicates an insert which fits into a recess or cutawa portion 24" in the main core section 11". h1s insert is of a size and shape to complete the core section, as will be readily understood from Fig. 9., On the face of the lower end of the main core section 11", opposing the inner wall of the insert 24 are formed a plurality of fine grooves 24 to permit the escape of air or gases and 11 and to insure the formation of the inwardly extending ribs on the casting. The grooves 24" lead to a conduit 24 preferably formed by cooperating grooves in adjoining faces of the insert" 24 and center section 11, through which conduit the air and gases esca e to lateral assageways 24" (see Fig. 4 between t e llfglel end of the insert and ader of the center section 11* formed by chamfering or beveling the upper inner edge of the insert24r The passageways communicate at their outer ends with the route 28. v

' metal The insert 24 is preferably fixed to the adjacent portion of the core section 11? by screws 24:

Assuming that the burners 21 have been operated to heat up the parts of the mold to the desired temperature and that the mold complete, includin core sections, is assembled, as illustrate in Fig. 1, the molten metal to be cast is brought to themold in any suitable manner, as by a ladle and is poured into the inlet ort 20 of the gate 20.

t descends through t e gate and enters the mold cavity A. I prefer to use a te 20 such as illustrated in the drawings scenes of the peculiar advantages which it possesses in connection with the casting of a cup-shaped article havin inwardly extending bosses and ribs or'eit er of them. The construction of the gate is such that a liquid seal is formed at 20' as the metal flows through the gate. This seal after it is formed tends to preclude the passage of air and gases, and also oxide and other fore' materials, into the mold cavity A and to materially reduce splashing of the metal within the gate during the curing. Splashing further is substantiall y eliminated by formin the wall 20? in such way that the ows smoothly along it and thence 1nto the cavity A. Air and gases within the mold cavit escape in the well-known manner throug the vents provided as hereiubefore described. The metal rises from the bottom of the mold cavity upwardly until it engages with the lower end of the inserts 23, when the casting B is com leted, having in this example two inwar y extending tubular bosses, b b, and two inwardl extending 'ribs b disposed at rig t angles to each other. The weight of the metal in the upper ortion of the. gate serves t force the met into the mold cavity to complete the casting, the u per end wall of thecasting being substantially in line with the upper portion of the gate which directlyfeeds it. By reason of the chilling effect of the molten metal of the cavity walls, the arrangement of the feeder section of the gate in relation to the mold cavity, the relatively large volume of the said feeder section and the relatively small volume of the passage between it and the mold cavity, and the maintaining of a relatively high temperature of the metal in the gate, the metal in the cavity freezes progressively from points most remote from the gate toward the gate and finally in the gate itself, the molten metal in the gate being thus drawn upon to make up for crystallization shrinkage'of the metal in the mold cavity. This result, which is of great importance in j securing sound castings is the more effectively and reliably attained by reason of the presence of the eutectic umformly distributed through the alloy and i drawn there rom, whereupon t acting, by virtue of its low freezing point, to maintain communication between the molten metal in the ate and points remote therefrom in the mol% cavity until metal at said points has frozen. After the pouring, I preferably next remove the core sections 15, 15, by ulling endwise each of them out of the mold or at least out of engagement with any part of the casting. Next,

preferably, I ease oil the locking devices somewhat and remove the main or center section 11 of the core by withdrawing it axially or longitudinally upward and away from the rest of the mold. Then b grasping the handles 11 I move bodily laterally each of the core sections 11so as to free it from alinement with any part of the adjacent casting boss I) see Fig. 10, and then withdraw each of t c said core sections 11 axially or longitudinally from the mold. Then the mold sections 3, 4, are unlatched and moved away from each other a suflicient distance to ermit the castingto be withey are a ain moved into engagement with each ot er, latched and the operation repeated.

The temperature of the parts 3, 4, may be maintained at about 800' degrees Fahrenheit and that of the core pins 15 at about 300 degrees Fahrenheit. The main core section may be maintained at slightly lower temperatures than the mold parts 3, 4, and the walls surrounding the gate 20 me be maintained even above 800 de ees Fa re heit where desired, to insure t at the metal in the gate will remain in liquid condition longer than that in the mold cavity. In

this connection it is desirable that the passage leading from the u right feeder section of the gate to the mo d cavity should be short and narrow as indicated in Fig. 10, as this helps to insure the above described progressive freezin of the metal first in the mold cavity, t en in the said passage and last in the gate.

I have already set forth the internal structural characteristics of the castings produced b my imp roved process, and I may now ad that where the period of time that a casting of the character to which my invention relates, remains in the mold is a factor in the production of a casting havin the desired internal structure, my improve process will be found to be of large advantage in enabling the operator or operators to produce one after the other in rapid succession castings which have been permitted to remain in the mold a prescribed time and having a given time-temperature treatment in the process of making Inasmuch as a eutectic is a conglomerate, that is, a physical mixture of two or more metallographic constituents, the excess substance will be of the same composition as one constituent of the eutectic. There is therefore, a tendency for the excem substance to absorb the like constituent from the eutectic. This is especially true where the excess substance exists in a comparatively large quantity and where the eutectic exists in a comparatively small quantity. It sometimes ha pens that some or even practically all 0 one constituent of a eutectic is absorbed by the excess substance, leaving the remaining constituent or constitnents of the eutectic isolated but occupying the .position that would otherwise be occupied by the eutectic. It also frequently happens in the case of aluminum rich alloys containing copper, that material not true eutectic but occupying the position of the eutectic, is in reater quantity than the true eutectic. his. is brought about by rapid sol' ification of the metal with concentration of the low melting point mixtures, includin mixtures other than true eutectic, towar the surfaces of the ains of excess substance as cooling and soli ification roceed. After the metal has become comp etely solid, if its temperature is held immediately below the freezing point for some time, a readjustment by diffusion will occur in the composition of the metal and the extra low melting point metal at the surfaces of the grains of excess substance, that is, in the place normally occupied by the eutectic, will be absorbed into the excess substance itself. But with rapid cooling, time may not be given immediately below the freezin point for this readjustment by diffusion an consequently some of the low melting point portion will be trapped in the position of the eutectic and it IS difiicult to distinguish this from true eutectic. The position occupied by the eutectic around the' grains of excess substance, especially when it is present in an allo in any such proportion as has been specific herein, gives it the a pearance in section of a. net-work. An as a eutectic which has been robbed of more or less of a constituent or a eutectic which has been supplemented by other low meltin point metal, retains the same networt form and distribution characteristic of eutectic, in dealing with metallographic structures, metallurglsts now commonly designate the said net-work formation as eutectic whether it be true eutectic or eutectic that has been robbed of a constituent or eutectic that has been supplemented by other low melting mixtures. Therefore, when I refer herein to eutectic it is to be understood that I use the term in this broad sense.

I appreciate the fact that my inventions herein disclosed lprobably constitute subjects-matter for ifi'erent applications for Letters Patent, and accordin ly-of even date herewith I have executed an filed an application relating to my improved apparatus herein disclosed. (See application Se No.

tions of and widely diflering embodiments and applications of my invention will suggest themselves, without departin from the spirit and scope thereof. My isclosures and the descriptions herein are purely illustrative and are not intended tobe in any sense limiting.

What I claim is:

1. The process of making internal combustion motor piston castings, which consist in bringing a molten metallic alloy, of relativel low specific gravity and high crystallizatibn shrinkage and coeflicient of heat conductivity and in which a eutectic will exist after final freezing, against chilling surfaces constitutin the walls of a mold cavity of the desire piston shape, and causing progressive settlng of the casting accompanied at all times by compensation with molten metal for crystallization shrinkage and complete solidification with the eutectic substantially surrounding the excess substance of the metallic alloy.

2. The process of making internal combustion motor piston castings, which consists in bringing a molten metallic alloy, of relatively low specific gravity and high crystallizatlon shrinkage and coeflicient of heat conductivity and in which a eutectic will exist after final freezing, against chilling surfaces constituting the walls of a mold cavity of the desired piston shape, and causing r0- gressive setting of the casting to take p ace from points relatively remote from those at which the molten metal enters the mold cavity, accompanied at all times by compensation with molten metal for or stallization shrinkage and complete solidi cation with the eutectic substantially surrounding the excess substance of the metallic alloy.

3. The process of making internal combustion motor piston castings, which consists in pouring a molten alumlnum alloy containing copper, iron and magnesium, or any of them, under the action of gravity, against chillin surfaces arranged to give the desired s a e to the casti and causing the setting 0 the metal in i ie castin to take place progressively with the liqui metal in the casting at all times in communication with the necessary volume of additional liquid metal to compensate for crystallization shrinkage in the casting and with the eutectic substantially surrounding the excess material when the casting is solidified.

4. The process of making internal combustion motor piston castings, which consists in bringing a molten metallic alloy having relatively low specific gravity and relatively hi h coeflicient of heat conductivity against chi 1- ing surfaces disposed to form a piston casting havin hollow wrist pin bosses, removing the chllling surfaces which extend into the wrist pin bosses, then removing the chilling surfaces for the remaining inner walls of the casting, and then removing the casting therefrom.

5. The process of making internal combustion motor piston castings, which consists in bringin a molten metallic alloy having a relative y low s ecific gravity and a relatively hl h coe cient of heat conductivity against c 'lling surfaces shaped to form a skirted piston casting having hollow Wrist pin bosses, the chilling walls for shaping the holes through the wrist pin bosses being maintained at a lower temperature than the other chilling walls for the mold cavity, then removing the chilling walls for the wrist in bosses, then removingthe other walls or the interior of the piston casting, and thenremoving the casting.

6. The process of making internal combustion motor skirted piston castings in a mold comprising outer walls and inner walls formed by a plurality of elongated removable main core sections shaped and disposed to determine the thickness of the walls of the'casting and to form internally extending wrist pin bosses, together with elongated removable core sections for the wrist pin bosses, said process consisting in introducing a molten metallic alloy having a low specific avity and a high coeflicient of heat conuctivity into the mold cavity, then removing the core sections of the wrist pin bosses, then removing one of the main core sections not engaging the internal wrist pin bosses by withdrawing it longitudinally parallel to the axis of the mold cavity, then withdrawing the main core sections engaging1 the internal wrist pin bosses by moving t em laterally to free them from the wrist pin bosses and then longitudinally along the axis of the mold cavity, and then withdrawing the casting. V

7. e process of making skirted piston castings having internally extending hollow wrist pin bosses, which consists in positionin within the cavity of a permanent mold y permanentside core sections having recesees inwhich are formed the internally extending wrist pin bosses, sliding a nent central core section between said side rmacore sections to properly position the latter and complete the main core, inserting permanent core pins in the said recesses in the side core sections, then introducing molten metal into the mold cavity thus formed, then removing the core pins for the wrist pin bosses, then removing the center section of the main core by withdrawing it along the axis of the mold cavity, then moving each side core section bodily laterally within the castin and then drawing it outwardly along the axls of the mold cavity, and then removing the casting.

' and complete the main core, inserting 8. The process of making skirted piston castings having internally extending hollow wrist pin bosses, which consists in positioning within the cavity of a permanent mold body permanent side core sections having recesses in which are formed the internally extending wrist pin bosses, sliding a permanent central core section between said side core sections to properly position the latter P manent core pins in the said recesses in the side core sections, maintaining said core pins at a relatively lower temperature than the other walls of the mold cavity, then introducing molten metal into the mold cavity thus formed, then removing the core pins for the wrist pin bosses, then removin the center section of the main core by withdrawing it along the axis of the mold cavity, then movin each side core section bodily laterally wlthin the casting and then'drawing it outwardly along the axis of the mold cavity, and then removing the casting.

9. The rocess of makin skirted piston castings or internal com ustion motors which consists in causin molten metallic alloy in' which a eutectic Wlll exist after final freezing and which alloy has a relatively low specific gravity and a relatively high crystallization shrinkage and coeflicient of heat conductivity, to flow under the action of gravity into a mold cavity, the walls of which are constituted of metal maintained at a chilling temperature as compared with the temperature of the molten alloy, causing progressive setting of the casting in the presence of a surp us of molten alloy which is drawn upon to compensate for and fill up cavities due to crystallization shrinka causing solidification of the castin to he efl'ected with the eutectic substantially surrounding the excess substance, and then freeing the casting from the walls constituting the mold cavity.

10. The process of making an internal combustion motor piston casting which consists in disposing chilling walls to provide a mold cavlty shaped to form a skirted pis ton casting having wrist pin bosses, causing a molten metallic alloy havin a relatively low specific gravity and a re atively high flow in opposite directions to fill said cavity,

causing the progressive setting of said casting and at the same time mainta ning a surplus of molten alloy in communication with the liquid metal in the casting to compensate for shrinkage therein due to crystallization, and then freeing the casting from the chilling walls constituting the mold cavity.

11. The process of making an internal combustion motor piston casting which consists in disposing chilling walls to provide a mold cavity shaped to form a skirted piston casting having wrist pin bosses, causing a molten alloy having a high crystallization shrinkage and in which arelatively small amount of eutectic will exist after final freezing to enter under the influence of gravity said mold cavity intermediate the wrist pln boss recesses therein and to flow in opposite directions to fill said recesses and cavity, and causing freezin of the metal in the mold cavity to take p ace substantially without the formation of cavities due'to crystallization shrinkage and in such manner that in the resulting structure the eutectic will substantially surround the excess material.

12. The process of making internal oombustion motor skirted piston castings in a mold comprisin outer walls and inner walls formed by a p urality of elongated removable main core sections shaped and disposed to determine the thickness of the walls of the casting and to form internally extending projections including wrist pin bosses on the side walls of said casting, together with elongated movable core sections for the wrist pin bosses, said process consisting in introducinfg a molten metallic alloy havin a low speci c ravity and a high co-efiicient of heat con uctivlty into the mold cavity, then removin the core sections of the wrist pin bosses, tlien removing one of the main core sections free for lon 'tudinal movement parallel to the axis of t e mold cavity, then withdrawing the remaining core sections by moving them first laterally to free them from said internal projections and then longitudinally of the axis of the mold cavity, and then withdrawing the casting.

13. As a new article of manufacture, an internal combustion motor piston casting made of a metallic alloy in which exists a eutectic, said alloy having a relatively low specific gravit and a relatively high crystallization shrinkage and coeflicient of heat conductivity and the castin being fine grained and substantially wit out cavities due to crystallization shrinkage and having the eutectic substantially surrounding the excess substance.

14. As a new article of manufacture, an internal combustion motor piston casting made of a metallic alloy in which a relatively small volume of eutectic exists after freezin and substantially surrounds the excess su stance and which alloy has a relatively low specific gravity and a relatively high crystallization shrinkage and coefiicient of heat conductivity, the structure of the casting being substantially free from cavities due to crystallization shrinkage and relatively fine'grained.

15. As a new article of manufacture, an

internal combustion motor piston casting made of an alloy consisting predominantly of aluminum and containing other elements such as magnesium, copper, and iron, in proportions to produce a relatively small quantity of eutectic in the casting after freezing, the casting having the said eutectic substantially surroundin the excess substance therein and being %ne grained and substantially free from porosity due to crystallization shrinkage. v

16. As a new article of manufacture, an internal combustion motor piston casting made of any alloy consisting predominantly of aluminum and containing other elements such as magnesium, copper, and iron, in proportions to produce a relatively small quantity of eutectic in the casting after freezing, said casting having the said eutectic substantially surrounding the excess substance therein and being fine grained and substantially free from cavities due to crystallization shrinkage and entrapped air and other gases.

17. As a new article of manufacture, an internal combustion motor piston casting made of an alloy consisting predominantly n El of aluminum with its component parts selected and proportioned to produce a relatively small quantity of eutectic in the casting'after freezing, the casting having the sald eutectic substantially surrounding the excess substancetherein andzbeing fine grained and substantially free from porosity due to crystallization shrinkage.

18. As a new article of manufacture, an internal combustion motor piston casting made of an alloy consisting predominantly of aluminum with its component parts selectedand proportioned to produce a relatively small quantity of eutectic in the castin after freezing, the casting having the said eutectic substantially surrounding the excess substance therein and being fine grained and substantially free from cavities no to crystallization shrinkage and entrapped air and other gases.

19. As a new article of manufacture, an

internal combustion motor iston casting made of ametallic alloy in whlch a relatively small volume of eutectic exists after freezing and substantially surrounds the excess substance, and which alloy has a relatively low specific gravity and a relatively high crystallization shrinka and coefiicient of heat conductivity, sai casting being substantially free from cavities due to crystallization shrinkage and of relativel fine-grained structure resulting from setting or chillin of the alloy between chilling surfaces an under the gravity action of the metal poured to make the casting.

20. As a new article of manufacture, an internal combustion motor piston casting made of an alloy consisting'predominantly of aluminum and containing copper, magnesium and iron, the casting having-chilled walls and being fine grained and substantially free from porosity due to crystallization shrinkage.

21. As a new article of manufacture, an

internal combustion motor piston casting made of an alloy consisting predominantly of aluminum and containing other elements such as copper, magnesium and iron, -in proportions to produce a relatively small quantity of eutectic in the casting after freezing, the casting having the said eutectic substantially surrounding the excess substance therein and having chilled walls.

22. As a new article of manufacture, an internal combustion motor piston casting made of an alloy consisting predominantly of aluminum, the casting having chilled walls and bein formed with inwardly extending integra hollow wrist pin bosses with internal walls chilled to a greater extent than other portions of the casting.

23. The process of making permanent mold castings of metallic alloys having high crystallization shrinkage which consists in so proportioning the constituent metals and so controlling the time and temperature factors in alloying and casting that on freezing the eutectic is in suitable quantity to substantially surround the excess substance, and in introducing the molten alloy into a mold cavity having walls of high heat conductivity in such manner that each point in the cavity is in communication with a supply of i made of an alloy of low specific gravity and In testimony whereof I affix my signature,

high coefficient of hleat conductiv1ty,inhci)min the presence of two Witnesses. parison with iron t e casting having 0 i led w r outer walls and being formed with inwardly JOSEPH BAMBLIG' 5 extending integral hollow wrist pin bosses Witnesses:

with internal walls chilled to a greater extent VERNON E. GARDNER, than other portions of the casting. M. R. LAIRD. 

